The present invention relates to an image processing method, an image processing apparatus, and a recording media on which an image processing program is recorded, and in particular, to an image processing method, an image processing apparatus, and a recording media on which an image processing program is recorded in which an edge zone and a flat zone of an original image are both optimally processed in accordance with respective features thereof to generate an output image having picture quality improved as compared with picture quality of the original image.
JP-A-8-161483 describes an image processing method in which luminance change values are calculated in a plurality of predetermined directions centered on a given point of an input image, a direction of a minimum value of the luminance change values, i.e., a minimum change direction is selected, and a one-dimensional flattening process is conducted in accordance with data of a plurality of points in the minimum change direction.
Several filtering methods of removing noise of an image have been described in xe2x80x9cDirectional Image Filter Separating Edge and Flat Zonesxe2x80x9d written by Taguchi et al in pages 2345 to 2350 of xe2x80x9cIEICE Technical Reportxe2x80x9d, Vol. J80-D-II, No. 9 published in September 1997.
An image includes an edge zone including a contour line and a boundary area between bright and dark regions of the image and a flat zone other than the edge zone. Image data varies in features or characteristics between the edge and flat zones. Consequently, when the same one-dimensional nonlinear flattening process is achieved for the image data of the edge and flat zones, it is impossible in some cases to obtain desired picture quality for one or both of the edge and flat zones. That is, a one-dimensional nonlinear flattening process optimal to the edge zone is not necessarily optimal to the flat zone and vice versa depending on cases.
It is therefore an object of the present invention to provide an image processing method, an image processing apparatus, and a recording media on which an image processing program is recorded in which the flattening process is appropriately achieved for both of the edge and flat zones in accordance with the respective features thereof to thereby generate an output image with improved picture quality.
In accordance with the present invention, there is provided an image processing method in which an original image is recognized by separating an edge zone and a flat zone from the image. A first one-dimensional nonlinear flattening process effective for the edge zone of the image is conducted for the image to obtain first data. A second one-dimensional nonlinear flattening process effective for the flat zone of the image is conducted for the image to obtain second data. Using the first and second data respectively for the edge and flat zones, an output image is reconfigured.
In accordance with the present invention, there is provided an image processing apparatus including a unit to execute the image processing method above.
In accordance with the present invention, there is provided a computer-readable recording media on which the image processing method is stored in the form of a program code.